There isn't a formula. I don't believe that admission boards insert all of your data into a machine that spits out a ranking of your suitability to practice anesthesia. Whether an applicant shadowed just once in order to complete the requirement or half a dozen times most likely makes very little difference as a standalone statistic.

Hundreds of people apply and scant few are admitted. If I were part of an admissions committee, I would seek out students whose data and interview demonstrate their burning desire to practice in the field.

How do you know if someone is passionate about the prospect of studying and practicing anesthesia? They go above and beyond. They don't ask if 8 hours is enough. They want to shadow as much as possible because they love the experience. They don't wonder if the school will accept a C in gen chem. They seek out opportunities for more exposure to the field. They study pertinent topics even when there is no test, but simply because they love the science and art.

Don't try to discover a path to the "magical" application. Pursue the career in all areas with the passion of someone whose life depends on it and it will show.